\\[-1.8ex] Soil Heterogeneity & $-$0.041 & $-$0.043 & $-$0.050$^{*}$ & $-$0.050$^{*}$ \\ 
  & (0.032) & (0.032) & (0.026) & (0.026) \\ 
\\[-1.8ex] 
Observations & 7,489 & 7,489 & 2,038 & 2,038 \\ 
R$^{2}$ & 0.676 & 0.677 & 0.626 & 0.626 \\ 
